1.) Astral Fire timer has never been what held BLM back from blowing out actually serious amounts of damage. Enochian timer management is the core mechanic that has made BLM somewhat challenging and fun to work around and is the one mechanic I DON'T want BLM to lose. Do that and you just made BLM like literally every other caster. Thank you, no.

2.) Fire IV's whole challenge and minigame is getting them off consistently without interruption. Making them shortcasts like Ruin III just takes away from that fun. As for weave windows, you have a guaranteed weave window every 30s (Thunderhead refresh), you have a shortcast on AF3 Blizzard III cast and UI3 Fire III cast (non-proc), you generate a stack of Polyglot every 30s and at Lv90+ you have instant Paradox, guaranteeing an instant Fire III.

The most frequently weaved ability besides Transpose, Sharpcast, has been removed, reducing the necessity of such shortcasts. If they truly insist on never returning Umbral Paradox, then at most the shortcast Blizzard IV could be nice for Transpose Firestarter to conserve Polyglot.

As for the levelling experience, you don't actually "just" spam Fire I over and over at Lv2-59. What could be done however is some stabilisation and making the Firestarter proc guaranteed, if at least at Lv54+ (old Sharpcast level).